Today marks 80 years since three Japanese midget submarines entered Australia’s Harbour.

The Japanese made advances across the Pacific in World War II in late May 1942, and the events that followed became known as the ‘Battle for Sydney’.

21 sailors were killed including 19 Australians and two Brits.

Military Historian Mat McLachlan told Ben Fordham it was an unprecedented time.

“There was this real feeling they were going to take over much of the Asia-pacific and there was nothing we could do about it.”

The attack called for improved defences at key military sites across Australia.

Press PLAY below to hear the full interview

Image: Nine